Method of solidifying molten pitch



.May' 12, 1970 w. L. M HENRY ETAL 0 METHOD OF'SOLIDIFYING MOLTEN PITCH v a Sheets-Sheet 1 Filed May 16, 1968 W/LBUR L. McHE/VRY, SAM S. SLOSMA/V a J/MM/E r. SMITH y Attorney May 12, 1970 w. L. M HENRY ETAL METHOD OF SOLIDIFYING MOLTEN PITCH Filed May 16, 1968 2 Sheets-Sheet 2 JZ-l 2a 1a 20 2a IN VE N TORS.

United States Patent 3,511,770 METHOD OF SOLIDIFYING MOLTEN PITCH Wilbur L. McHenry, Crown Point, Sam S. Slosman, Hebron, and Jimmie T. Smith, Hobart, Ind., assiguors to United States Steel Corporation, a corporation of Delaware Filed May 16, 1968, Ser. No. 729,793 Int. Cl. C10c 3/00 US. Cl. 208-39 Claims ABSTRACT OF THE DISCLOSURE Molten pitch is poured on a layer of small pieces of pitch on a cooling slab. The depth of the layer is such that the molten pitch will not remelt the layer to the slab. After cooling, mobile loading equipment easily lifts the solidified pitch for transfer to shipping means and then provides another layer of small pieces of pitch for the next shipment.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a method of disposing of molten pitch and, in particular, to a method for preventing adhesion of hot pitch to a cooling slab, thus facilitating the removal of the pitch when solid, with a minimum of cost and dust.

Description of the prior art The best method of solidifying molten pitch of which we have knowledge is disclosed in Go'bla and Tate Pat. No. 3,304,252, dated Feb. 14, 1967. As there described, a layer of cooling water is provided on a slab to a 'predetermined depth of at least about one-half inch. Molten pitch is then poured on the slab to provide a layer of solidified pitch having a depth approximating the depth of the water layer. Additional molten pitch is then poured on the solidified pitch layer until the required quantity thereof has accumulated. The thickness of the solidified pitch layer is such that the additional molten pitch will not remelt it to the slab. The additional molten pitch is air cooled or cooled by a water spray thereon.

While this method has eliminated many of the disadvantages of prior practices, it has been found that industrial water, for example, lake or river water used in this method in coke-oven plants, does include contaminants that can affect the pitch product deleteriously. At temperatures below 32 F., the use of and the sewage disposal of the relatively large quantities of water used in this method create problems that limit the use of this method. Conversely, in hot summer weather when industrial water is over 65 F., its effectiveness in this method is reduced.

SUMMARY OF THE INVENTION After mobile equipment has loaded an order on a railroad car or trucks, sufficient solidified pitch remains in a pitch bay for the mobile equipment to spread it on a cooling slab to a predetermined depth, as a layer of small pieces of pitch. When there is a change in pitch specification the layer is secured from a storage pile. Thereafter, molten pitch is poured onto said layer until the required quantity thereof has accumulated. The depth of said layer is such that the molten pitch will not remelt said layer to said slab. The molten pitch is cooled until solidified and is then broken up and loaded by the mobile equipment.

BRIEF DESCRIPTION OF THE DRAWINGS A complete understanding of the invention may be obtained from the following detailed description and ex- 3,511,770 Patented May 12, 1970 planation which refer to the accompanying drawings illustrating the present preferred practice.

In the drawings:

FIG. 1 is a plan view of a pitch-cooling bay and auxiliary equipment for carrying out the method of our invention;

FIG. 2 is a vertical section taken on a line 11-11 of FIG. 1;

FIG. 3 is a front elevation showing the access gate to the bay taken on a line III--III of FIG. 1; and

FIG. 4 is a vertical section taken on a line IVIV of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in detail to the drawings, a typical pitchcooling bay comprises a concrete slab 2 having disposed therearound beams 4, held in place on the slab by anchor bolts 6. The structure includes spaced, vertical beams 8 disposed on the web of beams 4 and welded thereto. The inner, vertical periphery of the structure is defined by the inner flanges of beams 4, plates 10 supported thereon and attached to beams 8, and angles 12 longitudinally disposed on and attached to beams 8 and plates 10. An opening 14 in the structure and a ramp 16 leading thereto permit mobile equipment to enter the bay and handle the pitch. During molten pitch flow, opening 14 is closed by a gate 18. Gate 18 comprises a channel 20, supporting plates 22, 24, stiffener plates 26 and brackets 28 for attaching hooks and cables to move the gate. Spaced studs 30 welded to beams 4 pass through slots 32 in gate 18. When the gate is positioned, nuts 34 may be applied to bolts 30 to secure the gate. The inner periphery of the pitch bay structure is appreciably higher than the gate to permit mobile loading equipment to push and pile pitch lumps against the structure in a loading operation.

A fire hydrant 36, equipped with a hose 38 and a conventional nozzle 40, provides water for cleaning the slab when there is a change in pitch specifications. Molten pitch is pumped from a source (not shown) through a pipe 42 and may be introduced to the bay at spaced-apart positions by pipes 44, 46 controlled :by valves 48, 50 and 52. Cleaning water may drain through opening 14- and at the four corners through openings 54 between the beams 4.

In carrying out our invention mobile equipment provides to a predetermined depth a layer of pitch of the proper specifications. This pitch may be the remainder from the last shipment or from a stock pile thereof. The equipment spreads a layer of pitch on slab 2 to a substantially uniform depth. Broadly stated, the layer may be between the about 1" and 6" in depth, preferably be tween about 2" and 4". The depth used depends on the cube-in-air softening point of the pitch, which may vary between about C. and 190 C. and on the temperature of the molten pitch, which may vary between about C. and 250 C. In general the chosen pitch depth in its range, varies inversely with the softening point and directly with the temperature of the 'hot pitch. Thus a pitch layer may be decreased below about 2" to about 1", with out remelting the pitch layer so that it then sticks to the slab when the hot pitch is relatively low in temperature and has a relatively high softening point. A pitch layer may be more than about 4" and up to about 6" thick when the hot pitch is on the high side of the temperature range and its softening point is on the low side of the range. A layer may approach 6" and even go therebeyond to prevent remelting and sticking in the areas where the molten pitch is introduced to a bay by pipes 44 and 46. Any unnecessary pitch layer thickness costs that much more to spread. For normal coke-plant operation, the

'eferred 2" to 4" layer has been found generally satisctory and will allow for some variation in the level of e cooling slab. The above explanation, however, will rmit practice of our invention, when the pitch propties vary, for example, when handlingwood pitch, aslalt pitch, petroleum pitch or the like.

The small pieces of pitch may vary in size from dust pipeces as much as 4 inches in their maximum dimenms. At the beginning of the spreading operation the fch will contain pieces that vary in size up to several at intheir maximum dimensions. The pitch is quite able thus providing the layer of small pieces by such mm as dropping the bucket of the mobile equipment l the large pieces and by running the mobile equipment ck and forth over the pitch in the bay, preferably, with e bucket resting on the layer. Thereafter, the equipment ay 'be operated with the bucket suspended at the prefired distance above the slab, to provide a uniform layer pth and for further crushing. It is obvious that manual iormay be used exclusively or in addition to mobile uipment to break up the lumps and to provide a unirm layer. When the layer is provided, gate 18 is set in place. tlves 48 and 50 are opened and molten pitch is pumped 'ough pipes 42, 44 to the bay. The pitch thus spreads agressively and in an arc of increasing diameter over pitch layer to beams 4; Valve 50 may be closed and lve 52 opened to flow pitch through pipe 46 to the slab. us, molten pitch may beintroduced to slab 2 either 'ough pipe 44 or pipe 46, to the pipes alternately or in simultaneously. The molten pitch appears to float or roll along ontop of the pitch layer. The molten pitch :omes fused to the layer of small pieces of pitch as it ws over the pitch pieces and into the interstices there- :ween. When the required quantity of molten pitch has :umulated valve 48, valve 50 and/or valve 52 are sed. After cooling and solidification, gate 18 is removed and bile equipment enters the bay to break up the pitch lumps for subsequent loading and shipping. Breaking the pitch is surprisingly easy when the teachings of t invention are followed. The sensible heat in the fresh lten pitch serves to bind it to the pitch layer but is ufficient to remelt the layer so that it sticks to the slab. e top surface of the solidified pitch is smooth and ny. Surprisingly, the surface of solidified pitch adjacent slab resembles peanut brittle, except that it has a dull ck finish. The pitch fractures into manageable lumps l with a minimum formation of dust and fines. The

'ention has reduced production of fines to between about r v and 4% from the 20% of other coke-oven plants. specific example of the practice of the invention, givquantities involved, is set forth below. h pitch-cooling bay measuring about 71' x 71' having :oncrete slab was covered by mobile equipment with mt a 2'f to 3" layer of small pieces of pitch, the area ler pipe44 being about 4" to 5" thick. The pieces were mt 1" to 3" in size, with some smaller and larger ces. thereafter, gate 18 was set in place. Valves 48 and 50 re opened slowly and molten pitch pumped through es 42 and 44. A few minutes after the initial opening the valves, a maximum molten-pitch flow of about 200 tons per minute was developed and continued until required 11,000 gallons had been pumped over the :h layer to a depth thereover of about 4". This depth y be varied depending on the pitch requirements. the coal-tar pitch had a temperature of about 240 C. l a softening point of about 115 C., cube-in-air. When lring ,ceased the pitch was allowed to cool for about to 18 hours. Thereafter, gate 18 wa removed, mobile 4 equipment broke up the pitch into lumps with ease and loaded them for shipment. As the equipment moved ahead, cracks radiated about 6 to 8 feet from the bucket. There was no noticeable sticking of the solidified pitch to thesoftening point, the pouring of the pitch may be alternated between pipes 44 and 46 to prevent adhesion of pitch to the bay. Thus, for example, with high pitch temperature and a low softening point, the total heat to be removed becomes appreciably greater. After pouring for an interval from one pipe or position, that area may be cooled while pitch is poured from a spaced-apart position. Conversely, with high softening point and low temperature the pitch may be poured to a bay simultaneously from two spacedapart pipes or positions. In an area under a molten-pitch spout, the pitch layer may be several inches thicker than the average depth.

The invention is characterized by several distinct advantages. In the first place, our procedure for preventing pitch from adhering to a cooling slab is relatively simple,

inexpensive and effective. It permits handling of pitch more economically and with appreciably less dust than in the average coke-oven plant.

Secondly, the process can be easily varied to handle coal-tar pitches in relatively wide temperature and softening-point ranges. Utilizing the principles of this invention, other pitches with properties outside these limits may be processed.

Finally, the process eliminates some of the problems associated with the use of water, in the above identified Gobla et al. patent, as set forth hereina-bove. The solidified pitch product is dry.

Although we have disclosed herein the preferred prac- '7 tice of our invention, we intend to cover as well any change or modification therein which may be made without departing from the spirit and scope of the invention.-

We claim:

1. A method of solidifying molten patch which comprises providing a layer of small pieces of pitch on a cooling slab to a predetermineddepth, then pouring molten pitch onto said layer until the required quantity thereof has accumulated, the depth of said layer being such that the molten pitch will not remelt said layer in contact with said slab, and then cooling the molten pitch :to solidify the same.

2. A method as defined in claim 1 wherein said layer has a depth of at least about one inch.

3. A method as defined in claim 1 wherein said layer has a depth between about one and six inches.

4. A method as defined in claim 1 wherein said layer has a depth between about two and fourinches. v

5. A method as defined in claim 1 wherein said molten pitch is poured alternately from a first position and from a second position spaced from said first position.

References Cited UNITED STATES PATENTS 1,088,635 2/19'14 Stevens 208-39 3,304,252 2/1967 Gobla et al. 2O839 3,434,967 3/1969 Oldenburg 20839 DELBERT E. GANTZ, Primary Examiner V. OKEEFE, Assistant Examiner 

